Eastmond, P.J. and Jones, R.L. (2005) Hormonal regulation of gluconeogenesis in cereal aleurone is strongly cultivar-dependent and gibberellin action involves SLENDER1 but not GAMYB. The Plant Journal, 44 (3). pp. 483-493. ISSN 0960-7412Full text not available from this repository.
Storage oil is a major constituent in the cereal aleurone layer. The aim of this study was to investigate how gibberellin (GA) and abscisic acid (ABA) regulate conversion of oil to sugar in barley aleurone. The activity of the glyoxylate cycle enzyme isocitrate lyase (ICL) was surveyed in eight barley cultivars. Surprisingly, some cultivars do not require GA for the induction of ICL (e.g. Himalaya), whereas some do (e.g. Golden Promise). Furthermore, in Golden Promise, GA also stimulates triacylglycerol breakdown and enhances the net flux of carbon from acetate to sugar. In contrast, ABA strongly represses ICL activity and the flux of carbon from oil to sugar in both Golden Promise and Himalaya. Biolistics using a promoter reporter showed that GA and ABA regulate ICL at the level of transcription. Studies using barley and rice mutants and pharmacological agents show that GA-dependent induction of ICL activity is mediated by SLENDER1 and requires cGMP, but does not involve the transcription factor GAMYB. Gibberellin and ABA therefore act antagonistically to regulate gluconeogenesis in the aleurone layer as well as controlling the production and secretion of hydrolases into the starchy endosperm. We suggest that the variation between different barley cultivars might be a result of selective breeding to alter seed dormancy.
|Copyright, Publisher and Additional Information:||Open access copy available from the journal web site.|
|Keywords:||cereal; aleurone; gibberellin; abscisic acid; isocitrate lyase; gluconeogenesis|
|Institution:||The University of York|
|Academic Units:||The University of York > Biology (York)|
|Depositing User:||Open Access From Journal|
|Date Deposited:||23 Dec 2008 11:30|
|Last Modified:||23 Dec 2008 11:30|